A drug is injected into a patient and the concentration of the drug in the bloodstream is monitored. The drug's concentration, $C(t),$ in milligrams per liter, after $t$ hours is modeled by
$$
C(t)=\frac{5 t}{t^{2}+1}
$$
The graph of this rational function, obtained with a graphing utility, is shown in the figure.
(FIGURE CAN'T COPY)
a. Use the graph to obtain a reasonable estimate of the drug's concentration after 3 hours.
b. Use the function's equation displayed in the voice balloon by the graph to determine the drug's concentration after
3 hours.
c. Use the function's equation to find the horizontal asymptote for the graph.Describe what this means about the drug's concentration in the patient's bloodstream as time increases.